Fluoropolymer compositions

ABSTRACT

Compositions comprising a fluoropolymer having interpolymerized units derived from a nitrogen-containing cure site monomer and a catalyst composition are provided. The catalyst composition includes a compound having the general formula:  
     {RA} (−) {QR′ k } (+)    
     or the precursors thereof, wherein R is a nonfluorinated, partially fluorinated, or perfluorinated alkyl, alkenyl, cycloalkyl, cycloalkenyl, aryl or aralkyl, A is an acid- or acid-derivative anion, Q is phosphorous, sulfur, nitrogen, arsenic, or antimony, and each R′ is hydrogen or an alkyl, aryl, aralkyl, or alkenyl group, k is the valence of Q; and optionally (c) an alcohol of the formula R 2 —OH, wherein R 2  is an alkyl group which can be fluorinated.  
     Also provided are a method of making a fluoropolymer, a method of increasing induction time, and fluoropolymer articles containing curable or cured fluoropolymer compositions.

[0001] This application claims priority to pending prior applicationsU.S. Ser. No. 60/265,498, filed Jan. 31, 2001, U.S. Ser. No. 60/283,464,filed Apr. 12, 2001, and U.S. Ser. No. 60/283,535, filed Apr. 12, 2001.The entire disclosure of each prior application is considered part ofthe disclosure of this application and each is herein incorporated byreference.

TECHNICAL FIELD

[0002] This invention relates to curing fluoropolymer compositionshaving nitrogen-containing cure-site components and catalystcompositions for curing such fluoropolymers.

BACKGROUND

[0003] Fluorine-containing polymers (also known as “fluoropolymers”) area commercially useful class of materials. Fluoropolymers include, forexample, crosslinked fluoroelastomers, uncrosslinked fluoroelastomergums, and semi-crystalline fluoroplastics. Fluoroelastomers exhibitsignificant tolerance to high temperatures and harsh chemicalenvironments. Consequently, they are particularly well adapted for useas seals, gaskets, and other molded parts in systems that are exposed toelevated temperatures and/or corrosive chemicals. Such parts are widelyused in the automotive, chemical processing, semiconductor, aerospace,and petroleum industries, among others.

[0004] Fluoroelastomers often include a cure-site component tofacilitate cure in the presence of a catalyst. One class of usefulcure-site components includes nitrile group-containing monomers, forwhich organotin catalysts have been used as curing components. Suchcatalysts can leave undesirable extractable metal residues in the curedproduct and are undesirable for environmental reasons.Ammonia-generating compounds have also been used as a cure systemcomponent. These cure systems lack the desired level of rheology controlduring processing.

SUMMARY

[0005] In one aspect, the invention relates to a composition thatincludes (a) a fluoropolymer having interpolymerized units derived froma nitrogen-containing cure site monomer; (b) a catalyst composition thatincludes a compound having the general formula:

{RA}⁽⁻⁾{QR′_(k)}⁽⁺⁾  (1)

[0006] or the precursors thereof added separately or as a mixture;

[0007] and optionally (c) an alcohol of the general formula R²—OH,wherein R² is an alkyl group having from 1 to 20 carbon atoms, andwherein R² can be fluorinated.

[0008] In another aspect, the invention relates to a composition thatincludes (a) at least one fluoropolymer having interpolymerized unitsderived from a nitrogen-containing cure site monomer; (b) one or moreother fluoropolymer(s), which may have nitrogen-containing cure sitemonomers; (c) a catalyst composition that includes a compound having thegeneral formula:

{RA}⁽⁻⁾{QR′_(k)}⁽⁺⁾  (1)

[0009] or in certain cases the precursors thereof added separately or asa mixture; (d) a curative targeted to cure the one or more otherfluoropolymer(s); and optionally (e) an alcohol of the general formulaR²—OH, wherein R² is an alkyl group having from 1 to 20 carbon atoms,and wherein R² can be fluorinated.

[0010] In Formula (1), R is a C₁-C₂₀ alkyl or alkenyl, C₃-C₂₀ cycloalkylor cycloalkenyl, or C₆-C₂₀ aryl or alkaryl. R can contain at least oneheteroatom, i.e., a non-carbon atom such as O, P, S, and N, such as anether linkage. R can also be substituted, such as where one or morehydrogen atoms in the group is replaced with F, Cl, Br, or I. Each R canbe perfluorinated, partially fluorinated, or non-fluorinated.

[0011] A is an acid anion or an acid derivative anion, e.g., A can beCOO, SO₃, SO₂, SO₂NH, PO₃, CH₂OPO₃, (CH₂O)₂PO₂, C₆H₄O, OSO₃, O (in thecases where R is aryl or alkylaryl),

[0012] preferably COO, O, C₆H₄O, SO₃, OSO₃, or

[0013] most preferably COO, O, SO₃, and OSO₃; R′ is defined as R(above), and a particular selection for R′ may be the same or differentfrom the R attached to A, and one or more A groups may be attached to R;

[0014] Q is phosphorous (P), sulfur (S), nitrogen (N), arsenic (As), orantimony (Sb), and k is the valence of Q.

[0015] Each R′ is, independently, hydrogen or a substituted orunsubstituted alkyl, aryl, aralkyl, or alkenyl group having from 1 to 20carbon atoms, provided that when Q is nitrogen and the fluoropolymer inthe composition consists essentially of a terpolymer of TFE, aperfluorovinylether, and a perfluorovinylether cure site monomercomprising a nitrile group not every R′ is H. That is, when thespecified terpolymer is the only fluoropolymer in a composition, thegroup QR′_(k) is not NH₄, however, NR′₄, NHR′₃, NH₂R′₂, and NH₃R′ allfall within the scope of certain embodiments of the present invention.For example, when the cure site monomer is a nitrile-containingpartially-fluorinated vinyl ether, the group QR′_(k) can be NH₄.

[0016] Examples of suitable substituents include halogen (e.g.,chlorine, fluorine, bromine, iodine), cyano, OR³, and COOR³ groupswherein R³ is selected from hydrogen or the alkali or alkaline earthmetals, of which H, K, Na, and NH₄, are preferred, C₁ to C₂₀ alkyl,aryl, aralkyl, alkenyl, and R (as described above) groups. In addition,any pair of said R′ groups may be connected to each other and the Q atomto form a heterocyclic ring.

[0017] In other aspects, the invention provides a method of making afluoropolymer composition involving providing a composition as describedabove, mixing, shaping, curing (i.e., press-curing and optionallypost-curing), and optionally heat aging the composition. The inventionalso provides a method of improving scorch resistance (also calledscorch safety) in a curable fluoropolymer comprising the steps ofproviding a fluoropolymer comprising interpolymerized units derived froma nitrogen-containing cure site monomer and incorporating, into thefluoropolymer, a catalyst composition that includes a compound havingthe general formula: {RA}⁽⁻⁾{QR′_(k)}⁽⁺⁾ or the precursors thereof addedseparately or as a mixture, wherein R, A, Q, R′, and k are as definedabove in reference to Formula (1). The invention also provides articlescontaining the curable or cured compositions such as hoses, gaskets, andO-rings.

[0018] The compositions retain the advantages of the use ofnitrogen-containing cure site monomers (e.g., nitrile group containingcure site monomers) such as the high temperature performance propertiestypically achieved when organotin compounds or ammonia-generatingcompounds are used as the catalyst system with such cure site monomers.At the same time, the compositions exhibit improved properties, such ascompression set values, as compared to materials made using theorganotin compounds.

[0019] In addition, the inventive compositions have a controllable cureonset time (also termed induction time), and cure temperature such thatvarious processing operations such as molding or extrusion are possiblewithout the usual concern for premature curing (scorch). Thus, theinvention provides better scorch resistance than is available with knownammonia-generating cure systems, e.g., those described in WO 00/09569and WO 00/09603. These advantages are achieved while the post-curedcompositions of the present invention exhibit physical properties atleast as good as comparable fluoropolymer compounds made without theinventive compositions.

[0020] The inventive compositions are useful in applications where hightemperature exposure and/or harsh chemical exposure are expected.

[0021] The details of one or more embodiments of the invention are setforth in the description below. Other features, objects, and advantagesof the invention will be apparent from the description and from theclaims.

DETAILED DESCRIPTION

[0022] The composition of the present invention comprises afluoropolymer, a catalyst composition of Formula (1), and optionally, analcohol.

[0023] Suitable fluoropolymers include interpolymerized units derivedfrom a nitrogen-containing monomer and, preferably, at least twoprincipal monomers. Examples of suitable candidates for the principalmonomer include perfluoroolefins (e.g., tetrafluoroethylene (TFE) andhexafluoropropylene (HFP)), chlorotrifluoroethylene (CTFE),perfluorovinyl ethers (e.g., perfluoroalkyl vinyl ethers andperfluoroalkoxy vinyl ethers), and optionally, hydrogen-containingmonomers such as olefins (e.g., ethylene, propylene, and the like), andvinylidene fluoride (VDF). Such fluoropolymers include, for example,fluoroelastomer gums and semi-crystalline fluoroplastics.

[0024] When the fluoropolymer is perhalogenated, preferablyperfluorinated, it contains at least 50 mole percent (mol %) of itsinterpolymerized units derived from TFE and/or CTFE, optionallyincluding HFP. The balance of the interpolymerized units of thefluoropolymer (10 to 50 mol %) is made up of one or more perfluoro vinylethers and a nitrogen-containing cure site monomer (e.g. anitrile-containing vinylether or an imidate containing vinylether). Thecure site monomer makes up from about 0.1 to about 5 mol % (morepreferably from about 0.3 to about 2 mol %) of the elastomer.

[0025] When the fluoropolymer is not perfluorinated, it contains fromabout 5 to about 90 mol % of its interpolymerized units derived fromTFE, CTFE, and/or HFP, from about 5 to about 90 mol % of itsinterpolymerized units derived from VDF, ethylene, and/or propylene, upto about 40 mol % of its interpolymerized units derived from a vinylether, and from about 0.1 to about 5 mol % (more preferably from about0.3 to about 2 mol %) of a nitrogen-containing cure site monomer.

[0026] Suitable perfluorinated vinyl ethers include those of theformula:

CF₂═CFO(R² _(f)O)_(a)(R³ _(f)O)_(b)R⁴ _(f)  (2)

[0027] where R² _(f) and R³ _(f) are the same or are different linear orbranched perfluoroalkylene groups of 1-6 carbon atoms; a and b are,independently, 0 or an integer from 1 to 10; and R⁴ _(f) is aperfluoroalkyl group of 1-6 carbon atoms.

[0028] A preferred class of perfluoroalkyl vinyl ethers includescompositions of the formula:

CF₂═CFO(CF₂CFXO)_(d)R⁴ _(f)  (3)

[0029] wherein X is F or CF₃; d is 0-5, and R⁴ _(f) is a perfluoroalkylgroup of 1-6 carbon atoms.

[0030] Most preferred perfluoroalkyl vinyl ethers are those where, inreference to either Formula (2) or (3) above, d is 0 or 1 and each R²_(f), R³ _(f), and R⁴ _(f) contains 1-3 carbon atoms. Examples of suchperfluorinated ethers include perfluoromethyl vinyl ether,perfluoroethyl vinyl ether, and perfluoropropyl vinyl ether.

[0031] Other useful perfluorinated monomers include those compounds ofthe formula:

CF₂═CFO[(CF₂)_(e)(CFZ)_(g)O]_(h)R⁴ _(f)  (4)

[0032] where R⁴ _(f) is a perfluoroalkyl group having 1-6 carbon atoms,e is 1-5, g is 0-5, h is 0-5, and Z is F or CF₃. Preferred members ofthis class are those in which R⁴ _(f) is C₃F₇, e is 1 or 2, g is 0 or 1,and h is 1.

[0033] Additional perfluoroalkyl vinyl ether monomers useful in theinvention include those of the formula:

CF₂═CFO[(CF₂CF(CF₃)O)_(k)(CF₂)_(p)O(CF₂)_(q)]C_(r)F_(2n+1)  (5)

[0034] where k is 0-10, p is 1-6, q is 0-3, and r is 1-5. Preferredmembers of this class include compounds where k is 0 or 1, p is 1-5, qis O or 1, and r is 1.

[0035] Perfluoroalkoxy vinyl ethers useful in the invention includethose of the formula:

CF₂═CFO(CF₂)_(t)[CF(CF₃)]_(u)O(CF₂O)_(w)C_(x)F_(2x+1)  (6)

[0036] wherein t is 1-3, u is 0-1, w is 0-3, and x is 1-5, preferably 1.Specific, representative, examples of useful perfluoroalkoxy vinylethers include CF₂═CFOCF₂OCF₂CF₂CF₃, CF₂═CFOCF₂OCF₃, CF₂═CFO(CF₂)₃OCF₃,and CF₂═CFOCF₂CF₂OCF₃. Mixtures of perfluoroalkyl vinyl ethers andperfluoroalkoxy vinyl ethers may also be employed.

[0037] Perfluoroolefins useful in the invention include those of theformula:

CF₂═CF—R⁵ _(f),  (7)

[0038] where R⁵ _(f) is fluorine or a perfluoroalkyl of 1 to 8,preferably 1 to 3, carbon atoms.

[0039] In addition, partially-fluorinated monomers orhydrogen-containing monomers such as olefins (e.g., ethylene, propylene,and the like), and vinylidene fluoride can be used in the fluoropolymerof the invention, when the fluoropolymer is not perfluorinated.

[0040] One example of a useful fluoropolymer is composed of principalmonomer units of tetrafluoroethylene and at least one perfluoroalkylvinyl ether. In such copolymers, the copolymerized perfluorinated etherunits constitute from about 10 to about 50 mol % (more 1 @ preferably 15to 35 mol %) of total monomer units present in the polymer.

[0041] One or more other fluoropolymers may be incorporated into thefluoropolymer having interpolymerized units derived from anitrogen-containing cure site monomer. In addition, one or more otherfluoropolymers (which may include one or more copolymers) may be blendedwith the fluoropolymer (which may comprise a copolymer) havinginterpolymerized units derived from a nitrogen-containing cure sitemonomer. Such other fluoropolymers useful in a blend and/or copolymerinclude the entire array described above, and including homopolymers andcopolymers comprising the interpolymerized units mentioned above. Forexample, polytetrafluoroethylene (PTFE) and PFA(tetrafluoroethylene-perfluorovinylether) are useful.

[0042] The other fluoropolymer(s) may lack interpolymerized unitsderived from a nitrogen-containing cure site monomer and/or may includereactive sites adapted to a selected curative system. For example, twodifferent fluoropolymers, each having interpolymerized units derivedfrom a nitrogen-containing cure site monomer, such as a monomercomprising a nitrile group, may be blended to provide the fluoropolymerfor the present invention.

[0043] Another fluoropolymer may be included along with anothercurative, such as described below, to provide particular properties. Forexample, a fluoropolymer suitable for peroxide curing and a peroxidecurative may be included to improve chemical stability. Such a blendbalances the thermal stability and the chemical stability of theresultant blend, and also may provide economic benefits. These othercuratives also may be used to cure a blend of fluoropolymers havingnitrogen-containing cure site monomers without the need to include afluoropolymer lacking a nitrogen-containing cure site monomer.

[0044] The fluoropolymer(s) having nitrogen-containing cure sitemonomers preferably make up enough of the total fluoropolymer to provideincreased thermal stability over a comparative fluoropolymer that lacksthe composition of the present invention. This amount is generally atleast 25 weight percent (wt %), more preferably at least 50 wt %, of thetotal fluoropolymer in the invention. In some embodiments, thefluoropolymer is comprised entirely of nitrogen-containinginterpolymerized units.

[0045] The fluoropolymers may be prepared by methods known in the art.For example, the polymerization process can be carried out byfree-radical polymerization of the monomers as an aqueous emulsionpolymerization or as a solution polymerization in an organic solvent.When fluoropolymer blends are desired, a preferable route ofincorporation is through blending the fluoropolymer latices in theselected ratio, followed by coagulation and drying.

[0046] The nature and the amount of end groups are not critical to thesuccess in curing the fluoroelastomers of the invention. For example,the polymer can contain SO₃ ⁽⁻⁾ end groups generated by an APS/sulfitesystem, or the polymer may contain COO⁽⁻⁾ end groups generated by an APSinitiator system or the fluoroelastomer can have “neutral” end groups,e.g., those generated by the use of fluorosulfinate initiator systems ororganic peroxides. Chain transfer agents of any kind can significantlyreduce the number of end groups. If desired, such as for improvedprocessing, the presence of strong polar end groups such as SO₃ ⁽⁻⁾ canbe minimized and in the case of COO⁽⁻⁾ end groups, the amount can bereduced through post treatments (e.g., decarboxylation).

[0047] The cure site component allows one to cure the fluoropolymer. Thecure site component can be partially or fully fluorinated. At least onecure site component of at least one fluoropolymer comprises anitrogen-containing group. Examples of nitrogen-containing groups usefulin the cure site monomers of the present invention include nitrile,imidate, amidine, amide, imide, and amine-oxide groups. Usefulnitrogen-containing cure site monomers include nitrile-containingfluorinated olefins and nitrile-containing fluorinated vinyl ethers,such as depicted below:

CF₂═CFO(CF₂)_(L)CN  (8)

CF₂═CFO[CF₂CF(CF₃)O]_(q)(CF₂O)_(y)CF(CF₃)CN  (9)

CF₂═CF[OCF₂CF(CF₃)]_(r)O(CF₂)_(t)CN  (10)

CF₂═CFO(CF₂)_(u)OCF(CF₃)CN  (11)

[0048] where, in reference to the above formulas, L=2-12; q=0-4; r=1-2;y=0-6; t=1-4; and u=2-6. Representative examples of such monomersinclude CF₂═CFO(CF₂)3OCF(CF₃)CN,perfluoro(8-cyano-5-methyl-3,6-dioxa-1-octene), and CF₂═CFO(CF₂)₅CN.

[0049] Another suitable cure site component useful in the presentinvention is a fluoropolymer or fluorinated monomer material containinga halogen that is capable of participation in a peroxide cure reaction.Such a halogen may be present along a fluoropolymer chain and/or in aterminal position. Typically the halogen is bromine or iodine.Copolymerization is preferred to introduce the halogen in a positionalong a fluoropolymer chain. In this route, a selection of thefluoropolymer components mentioned above are combined with a suitablefluorinated cure site monomer. Such a monomer can be selected, forexample, from the general formula Z—R_(f)O_(x)—CF═CF₂, wherein Z is Bror I, R_(f) is a substituted or unsubstituted C₁-C₁₂ fluoroalkylene,which may be perfluorinated and may contain one or more ether oxygenatoms, and x is 0 or 1. When x is 0, examples of the bromo- oriodo-fluorolefins include: bromodifluoroethylene,bromotrifluoroethylene, iodotrifluoroethylene,1-bromo-2,2-difluoroethylene, and 4-bromo-3,3,4,4-tetrafluorobutene-l,and the like. When x is 1, examples of the bromo- or iodo-fluorovinylethers include: BrCF₂OCF═CF₂, BrCF₂CF₂OCF═CF₂, BrCF₂CF₂CF₂OCF═CF₂,CF₃CF(Br)CF₂OCF═CF₂, and the like. In addition, non-fluorinated bromo-or iodo-olefins, e.g., vinyl bromide and 4-bromo-1-butene, can be used.

[0050] The amount of cure site component in a side chain position of thefluoropolymer is generally from about 0.05 to about 5 mol % (morepreferably from 0.1 to 2 mol %).

[0051] The cure site component may also occur in the terminal positionof a fluoropolymer chain. Chain transfer agents or initiators are usedto introduce the halogen in a terminal position. Generally, a suitablechain transfer agent is introduced in the reaction medium during polymerpreparation, or derived from a suitable initiator.

[0052] Examples of useful chain transfer agents include those having theformula R_(f)Z_(x) wherein Rf is a substituted or unsubstituted C₁-C₁₂fluoroalkyl radical, which may be perfluorinated, Z is Br or I, and x isI or 2. Specific examples involving bromide include: CF₂Br₂, Br(CF₂)₂Br,Br(CF₂)₄Br, CF₂(Cl)Br, CF₃CF(Br)CF₂Br, and the like.

[0053] Examples of useful initiators include NaO₂S(CF₂)_(n)X, wherein Xis Br or I, and n is 1 to 10.

[0054] The amount of cure site component in a terminal position in thefluoropolymer is generally from about 0.05 to about 5 mol % (morepreferably from 0.1 to 2 mol %).

[0055] Cure site component combinations are also useful. For example, afluoropolymer containing a halogen that is capable of participation in aperoxide cure reaction may also contain a nitrogen-containing cure sitecomponent such as a nitrile group-containing cure site component.Generally, from about 0.1 to about 5 mol % (more preferably from about0.3 to about 2 mol %) of the total cure site component is incorporatedinto the fluoropolymer.

[0056] The fluoropolymer compositions of the present invention arecured, at least in part, using an organo-onium catalyst composition thatis the reaction product of an organo-onium (such as a halide, hydroxide,alkoxide, etc.) and an acid or acid salt. The catalyst compositionincludes a compound having the general formula:

{RA}⁽⁻⁾{QR′_(k)}⁽⁺⁾

[0057] wherein R, A, Q, R′, and k are as described above. Preferredanions include those wherein R is selected from alkyl, benzyl, andphenyl, and A is selected from COO, SO₃, and wherein A is O in the caseswhere R is aryl or alkaryl.

[0058] The catalyst composition of the invention can be hydrated oranhydrous. The catalyst can be in the form of a complex with waterand/or alcohol. The catalyst can be prepared by any known means. Oneexample for catalyst preparation involves converting acommercially-available hydroxide precursor to a benzoate or acetatecomplex. Another example involves reacting an onium halide with an acidmetal salt in a solvent, filtering the precipitated metal halide, andremoving the solvent. Other routes will be apparent to the skilledartisan.

[0059] More specifically, the RA anion in the catalyst of the presentinvention may be a carboxylate, alkoxide, sulfate, sulfonate, orphenolate. As used herein, “substituted” means substituted byconventional substituents that do not interfere with the desiredproduct, and “Ph” is phenyl. Suitable anions include thenon-perfluorinated anions of the general formula:

R_(x)—Ph_(y)—{(CH₂)_(n)—D}_(m)

[0060] wherein each R_(x) is the same or different alkenyl or alkyl of 1to 10 carbon atoms, which may be substituted or unsubstituted, x is 0 to5, y is 0 or 1, n is 0 to 10, m is 1 to 5, and D is selected from COO,OSO₃, SO₃, and 0 (when y is 1), provided that the sum of x and m is 6 orless and provided that x and y are not both zero.

[0061] Useful anion examples include Ph—COO, Ph—O, CH₃—(CH₂)_(p)—O—SO₃when p is 1 to 10, and carboxylates of the general formula R—COO whereinR is alkenyl, an alkyl of 1 to 10 carbon atoms, e.g., acetate orpropionate, or an aryl of 6 to 20 carbon atoms. Multi-carboxylates,multi-sulfates, multi-sulfonates, and combinations thereof are alsouseful, e.g.,

⁽⁻⁾OOC—(CH₂)_(n)—COO⁽⁻⁾ and ⁽⁻⁾OOC—(CH₂)_(n)—OSO₃ ⁽⁻⁾

[0062] wherein n is 0 to 10, and Ph—((CH₂)_(p)—COO⁽⁻⁾)_(q) wherein p andq are independently 1 to 4. A preferred species of bifunctionalcarboxylic acid is oxalic acid. In the case of multi carboxylates,sulfates, and combinations, the (CH₂)_(n) chain can also be fluorinatedor perfluorinated, e.g., OOC—(CF₂)_(n)—COO. The anion, RA, can also be amaterial selected from CF₃CF(CF₃)CH₂O and C_(n)F_(2n+1)CH₂O wherein n is0 to 100 (preferably 0 to 20, and more preferably 0 to 10). In addition,combinations of two or more compounds as described above can be used forRA in Formula 1.

[0063] Representative aromatic polyoxy compounds include thenon-perfluorinated di-, tri-, and tetraoxybenzenes, naphthalenes, andanthracenes, and bisphenols of the formula:

⁽⁻⁾O_(z)—Ph—G_(y)—Ph—O_(z) ⁽⁻⁾

[0064] wherein G is a bond or a difunctional aliphatic, cycloaliphatic,or aromatic radical of 1 to 13 carbon atoms, or a thio, oxy, carbonyl,sulfinyl, or sulfonyl radical, G and/or Ph are optionally substitutedwith at least one chlorine or fluorine atom, y is 0 or 1, each z is,independently, 1 or 2, and any aromatic ring of the polyoxy compound isoptionally substituted with at least one atom of chlorine, fluorine, orbromine atom, or carboxyl or an acyl radical (e.g., —COR, where R is Hor a C₁ to C₈ alkyl, aryl or cycloalkyl group) or alkyl radical with,for example, 1 to 8 carbon atoms. In the above bisphenol formula thatthe oxygen groups can be attached in any position (other than numberone) in either ring. Blends of two or more such compounds can also beused. The mono and bis complexes of the formula:

R_(x)—Ph—O—QR′_(k)

[0065] are also useful. A preferred class of these materials includesthe bisphenols, such as those having the general formula:⁽⁻⁾O—Ph—C(CX₃)₂—Ph—O⁽⁻⁾, wherein X is H, Cl, or F (e.g., bisphenol AF).When multifunctional acids are used, the mono-, bis-, andmulti-complexes with QR′_(k) can be used.

[0066] As is known in the art, an organo-onium is the conjugate acid ofa Lewis base (e.g., phosphine, amine, and sulfide) and can be formed byreacting said Lewis base with a suitable alkylating agent (e.g., analkyl halide or acyl halide) resulting in an expansion of the valence ofthe electron donating atom of the Lewis base and a positive charge onthe organo-onium compound. The preferred organo-onium compounds for thepresent invention contain at least one heteroatom, i.e., a non-carbonatom such as P, S, or N, bonded to organic moieties.

[0067] One class of quaternary organo-onium compounds particularlyuseful in the present invention broadly comprises relatively positiveand relatively negative ions wherein a phosphorus, sulfur, or nitrogengenerally comprises the central atom of the positive ion, and thenegative ion is an alkyl or cycloalkyl acid anion that may benon-fluorinated, partially fluorinated, i.e., at least one hydrogen atomis replaced with fluorine, provided that at least one hydrogen atomremains, or perfluorinated.

[0068] Examples of suitable precursor compounds when Q is phosphorousinclude tetramethylphosphoniums, tributylallylphosphoniums,tributylbenzylphosphoniums, dibutyldiphenylphosphoniums,tetrabutylphosphoniums, tributyl(2-methoxy) propylphosphoniums,triphenylbenzylphosphoniums, and tetraphenylphosphoniums. Thesephosphoniums can be hydroxides, chlorides, bromides, alkoxides,phenoxides, etc. The tetraalkyl phosphonium hydroxides and tetraalkylphosphonium alkoxides are preferred.

[0069] Another class of phosphonium compounds include those selectedfrom the group consisting of amino-phosphonium, phosphorane (e.g.,triarylphosphorane), and phosphorous containing iminium compounds.

[0070] The amino-phosphonium compounds useful in the present inventioninclude those described in the art, e.g., in U.S. Pat. No. 4,259,463(Moggi et al.).

[0071] The class of phosphonium compounds useful in this inventioninclude phosphorane compounds such as triarylphosphorane compounds; someof the latter compounds are known and are described in the art, see forexample, U.S. Pat. No. 3,752,787 (de Brunner), which descriptions areherein incorporated by reference. Such phosphorane compounds are firstreacted with an acid to form a salt, which salt is then used as acurative component. Some of the triarylphosphorane compounds useful inthis invention have the general formula:

[0072] wherein Ar is aryl, selected for example, from phenyl,substituted phenyl, e.g., methoxyphenyl, chlorophenyl, tolyl, and otherknown groups, e.g., naphthyl. R³ and R⁴ are selected from the groupconsisting of (1) separate groups selected individually from (a)hydrogen, methyl, ethyl, propyl, and carbalkoxy (C₁-C₆ alkyl) in thecase of R³, and (b) carbalkoxy (C₁-C₆ alkyl) cyano, and -CONH₂ in thecase of R⁴; and (2) a single group which together with the carbon atomto which the single group is attached form a cyclic group selected fromthe following:

[0073] Representative phosphonium compounds includebenzyltris(dimethylamino) phosphonium chloride, andbis(benzyldiphenylphosphine)iminium chloride.

[0074] Sulfonium compounds useful in this invention have at least onesulfur atom ionically associated with an anion and covalently bonded tothree organic moieties (R′) by means of carbon-sulfur covalent bonds.Said organic moieties can be the same or different. The sulfoniumcompounds may have more than one relatively positive sulfur atom, e.g.,[(C₆H₅)₂S⁺(CH₂)₄S⁺(C₆H₅)₂]2Cl⁻, and two of the carbon-sulfur covalentbonds may be between the carbon atoms of a divalent organic moiety,i.e., the sulfur atom may be a heteroatom in a cyclic structure.

[0075] A class of sulfonium compounds useful in the present inventionare salts having the formula:

[0076] wherein R⁵, R⁶, and R⁷ can be the same or different, providedthat at least one of such groups is aromatic, and such groups can beselected from C4-C20 aromatic radicals (e.g., substituted andunsubstituted phenyl, thienyl, and furanyl) and C1-C20 alkyl radicals.The alkyl radicals include substituted alkyl radicals (e.g.,substitutents such as halogen, hydroxy, alkoxy, aryl. Z is selected fromoxygen; sulfur; >S═O; >C═O; —SO₂—; —NR⁸—; where R⁸is aryl or acyl (suchas acetyl, benzoyl, etc.); a carbon-to-carbon bond; and —CR⁹R¹⁰—where R⁹and R¹⁰ are selected from the group consisting of hydrogen, C₁-C₄ alkylradicals, and C₂-C₄ alkenyl radicals.

[0077] Preferably, the sulfonium compounds have at least one aryl groupfor R′.

[0078] When Q is nitrogen, the preferred positive ion has the generalformula is NR′₄ or HNR′₃, wherein R′ is as described above.Representative quaternary organo-oniums useful as precursor compoundsinclude phenyltrimethylammoniums, tetrapentylammoniums,tetrapropylammoniums, tetrahexylammoniums, tetraheptylammoniums,tetramethylammoniums, tetrabutylammoniums, tributylbenzyl ammoniums,tributylallylammoniums, tetrabenzylammoniums, tetraphenylammoniums,diphenyl diethylamino ammoniums, triphenylbenzylammoniums,8-benzyl-1,8-diazabicyclo [5.4.0]undec-7-eniums,benzyltris(dimethylamino) phosphoniums, and bis(benzyldiphenylphosphine)iminiums. These ammoniums can be hydroxides, chlorides,bromides, alkoxides, phenoxides, etc. Of these positive ions,tetrabutylammonium and tetraphenylammonium are preferred.

[0079] When Q is As or Sb, the preferred positive ions includetetraphenylarsonium chloride and tetraphenylstibonium chloride.

[0080] Overall, the tetraalkylphosphonium compounds are more preferredfor the positive ion of the catalyst.

[0081] Mixtures of organo-onium compounds are also useful in thisinvention.

[0082] The precursors described above are generally commerciallyavailable (e.g., from Aldrich Chemicals, Milwaukee, Wis.) or may beprepared by procedures known in the art.

[0083] The acids or salts of hydrocarbons useful in preparing thecatalyst of the present invention have the general formula RCOOM, RSO₃M,ROSO₃M, or ROM. In these formulas, R 20 is as described above withFormula (1), and M is hydrogen, or an alkali or alkaline earth metal.

[0084] Representative materials for R are the carboxylates, sulfates,sulfonates, and phenolates described above.

[0085] In addition, blends of two or more catalyst compounds asdescribed above, which includes blends of two or more RA groups and/ortwo or more QR′_(k) groups, can be used.

[0086] The catalyst composition of the present invention can be preparedby any suitable method. For example, the two components of the activecomplex used as the catalyst composition in the present invention,{RA}⁽⁻⁾{QR′_(k)}⁽⁺⁾, can be incorporated separately as an acid or asalt, e.g., RAX wherein X is selected from hydrogen or the alkali oralkaline earth metals, of which H, K, Na, and NH₄, are preferred, andQR′_(k)Z, wherein Z is selected from an anion, which may be organic orinorganic, preferably Cl, Br, OH, OR³, or SO₄. The two components can beadded to the inventive elastomer gum separately or as a mixture. In thismethod, the active complex is formed in situ during processing, heating,and curing. To avoid contamination and the inclusion of extractables,which is especially important for clean applications (e.g.,semiconductors), the complexes should be prepared before incorporationinto the fluoroelastomer composition, and the resulting salts, XZ,should be filtered or washed out before the active complex isincorporated into the elastomer gum. Other suitable methods, which areknown in the art, also may be used to prepare the catalyst composition.For example, the two components of the catalyst composition can bedissolved into a suitable solvent (e.g., an alcohol) beforeprecipitating and filtering out the resulting salt, XZ. Salt formationcan be avoided by reacting the onium component as the onium-hydroxide oronium-alkoxide with the acid component of the catalyst composition(e.g., reacting Bu₄NOH with RCOOH). The active complexes can beincorporated into the elastomer gum when dissolved in a solvent or as adried compound. An excess of the QR′_(k) material (e.g., tetraalkylphosphonium chloride) or the free acid (e.g., RAH) does notdetrimentally affect the properties of the polymer.

[0087] An effective amount of the selected curative compound({RA}⁽⁻⁾{QR′_(k)}⁽⁺⁾) is used to crosslink the fluoropolymer. When theamount of curative is too low, the fluoropolymer may not crosslinksufficiently to develop the desired physical properties and/or maycrosslink more slowly than desired. When the amount of curative is toohigh, the fluoropolymer may crosslink into a material that is lesscompliant than desired and/or may crosslink too rapidly for the desiredprocess conditions. The selection of a particular composition can affectthe amount of curative desired. For example, the type and/or amount offiller selected may retard or accelerate curing relative to a similar,but unfilled, composition, requiring an appropriate adjustment in theamount of curative that is known to those skilled in the art.

[0088] The composition of the fluoropolymer also affects the amount ofone or more curatives. For example, when a blend of a nitrile containingfluoropolymer and another fluoropolymer lacking nitrile cure sites isused, an effective amount of a first selected curative compound is usedto crosslink the fluoropolymer having interpolymerized units derivedfrom a nitrile group-containing monomer together with an effectiveamount of a second selected curative compound used to crosslink theother fluoropolymer. The first and second selected curatives may havethe same or different composition. That is, either one or both selectedcuratives may function to crosslink either one or both fluoropolymers.

[0089] Generally, the effective amount of curative, which may includemore than one composition, is in the range of 0.2 to 10 millimolescurative per hundred parts of gum (mmhr) (more preferably 0.5 to 5mmhr).

[0090] One of the advantages of the present invention is controllablecure rheology. After an initial drop in torque, corresponding to anincrease in temperature of the material, the inventive compositions haveavailable a relatively long period of time (“induction time”) afterwhich the torque increases rapidly to its final or maximum value. Therapid increase in the torque corresponds to a rapid increase in theviscosity of the composition as it crosslinks. The induction time iscontrollable from seconds to several minutes. This allows a sufficientamount of induction time for a particular inventive composition to beformed or molded before the onset of cure. This rheology also provides arapid completion of the cure cycle after the cure onset, so the curecycle is not unnecessarily prolonged. Thus, compositions of the presentinvention can be completely formed or molded rapidly, cured to a statethat they can be handled without damage, and removed from the mold.

[0091] The fluoropolymer composition curing can also be modified byusing other types of curatives along with the catalyst of the presentinvention. Examples of such curatives are known and includebis-aminophenols (e.g., as described in U.S. Pat. Nos. 5,767,204 and5,700,879), bis-amidooximes (e.g., as described in U.S. Pat. No.5,621,145), and ammonium salts (e.g., as described in U.S. Pat. No.5,565,512). In addition, organometallic compounds of arsenic, antimonyand tin can be used, e.g., as described in U.S. Pat. Nos. 4,281,092, and5,554,680. Particular examples include allyl-, propargyl-,triphenyl-allenyl-, and tetraphenyltin and triphenyltin hydroxide.

[0092] The fluoroelastomer compositions of the invention can be curedusing one or more ammonia-generating compounds along with the catalystsdescribed above. “Ammonia-generating compounds” include compounds thatare solid or liquid at ambient conditions but that generate ammoniaunder conditions of cure. Such compounds include, for example,hexamethylene tetramine (urotropin), dicyandiamide, and metal-containingcompounds of the formula:

A^(w+)(NH₃)_(x)Y^(w−)  (15)

[0093] wherein A^(w+) is a metal cation such as Cu²⁺, Co²⁺, Co³⁺, Cu⁺,and Ni²⁺; w is equal to the valance of the metal cation; Y^(w−) is acounterion, typically a halide, sulfate, nitrate, acetate or the like;and x is an integer from 1 to about 7.

[0094] Also useful as ammonia-generating compounds are substituted andunsubstituted triazine derivatives such as those of the formula:

[0095] wherein R is a hydrogen or a substituted or unsubstituted alkyl,aryl, or aralkyl group having from 1 to about 20 carbon atoms. Specificuseful triazine derivatives include hexahydro-1,3,5-s-triazine andacetaldehyde ammonia trimer.

[0096] The fluoroelastomer compositions of the invention, including thenitrogen containing cure site monomer-containing fluoropolymer alone,can be cured using one or more peroxide curatives along with thecatalysts described above. Suitable peroxide curatives generally arethose which generate free radicals at curing temperatures, such as thosedescribed in WO 99/48939, the disclosure of which is herein incorporatedby reference. Dialkyl peroxide and bis(dialkyl peroxide), each of whichdecomposes at a temperature above 50° C., are especially preferred. Inmany cases it is preferred to use a di-tertiarybutyl peroxide having atertiary carbon atom attached to peroxy oxygen atom. Among the mostuseful peroxides of this type are2,5-dimethyl-2,5-di(tertiarybutylperoxy)hexyne-3 and2,5-dimethyl-2,5-di(tertiarybutylperoxy)hexane. Other peroxides can beselected from such compounds as dicutnyl peroxide, dibenzoyl peroxide,tertiarybutyl perbenzoate, a,a′-bis(t-butylperoxy-diisopropylbenzene),and di[1,3-dimethyl-3-(t-butylperoxy)-butyl]carbonate. Generally, about1 to 3 parts of peroxide per 100 parts of perfluoroelastomer is used.

[0097] Another curative useful in the present invention has the generalformula:

CH₂═CH—R_(f)—CH═CH₂,

[0098] wherein one or more H atoms may be replaced with halogen atoms,such as F, and R_(f) is a C₁-C₈ linear or branched and at leastpartially fluorinated alkylene, cycloalkylene, or oxyalkylene.Similarly, polymers containing pendant groups of CH₂═CHR_(f)— are alsouseful as curatives in the present invention. Such curatives aredescribed, for example, in U.S. Pat. No. 5,585,449.

[0099] The combination of catalyst and curative is generally from about0.01 to about 10 mol % (more preferably from about 0.1 to about 5 mol %)of the total fluoropolymer amount.

[0100] The fluoropolymer compositions can include any of the adjuvantscommonly employed in curable fluoropolymer formulations. For example,one material often blended with a fluoropolymer composition as a part ofa curative system is a coagent (sometimes also referred to as aco-curative) composed of a polyunsaturated compound that is capable ofcooperating with the peroxide curative to provide a useful cure. Thesecoagents are particularly useful in combination with a peroxidecurative. The coagent(s) can generally be added in an amount 5 equal tobetween 0.1 and 10 parts coagent per hundred parts fluoropolymer (phr),preferably between 1 and 5 phr. Examples of coagents useful with theorgano-onium compound of the present invention include triallylcyanurate; triallyl isocyanurate; tri(methylallyl) isocyanurate;tris(diallylamine)-s-triazine; triallyl phosphite; N,N-diallylacrylamide; hexaallyl phosphoramide; N,N,N′,N′-tetraalkyltetraphthalamide; N,N,NI,N′-tetraallyl malonamide; trivinylisocyanurate; 2,4,6-trivinyl methyltrisiloxane; andtri(5-norbornene-2methylene)cyanurate. Particularly useful is triallylisocyanurate. Other useful coagents include the bis-olefins disclosed inEP 0 661 304 A1, EP 0 784 064 A1 EP 0 769 521 A1, and U.S. Pat. No.5,585,449.

[0101] The optional alcohol has the general formula R²—OH, wherein R² isalkyl group having $5 from 1 to 20 carbon atoms, more preferably 6 to 12carbon atoms. R² can be fluorinated, e.g., R_(f)—CH₂—OH orR_(f)—CH₂CH₂—OH wherein R_(f) is a perfluoroalkyl, e.g., C_(n)F_(2n+1)where n is 1 to 20, or perfluorocycloalkyl, e.g., C_(m)F_(2m−1) where mis 3 to 20, or a C₁-C₂₀ fluoroalkenyl. R_(f) can also be partiallyfluorinated. As used herein, “partially fluorinated” means where one ormore F atoms in the alkyl group is replaced with H, Cl, Br, or I,provided at least one F atom remains. R_(f) can also contain at leastone heteroatom, i.e., a non-carbon atom such as O, P, S, or N.

[0102] While the addition of alcohol is not required, it may be helpfulto modify the viscosity and cure characteristics of the composition. Thealcohol is selected to be compatible in the overall composition. Thealcohol should also remain in a mixture of fluoropolymer with catalystduring milling operations. The alcohol preferably should evaporateduring subsequent processing at higher temperatures, such as duringpost-cure operations. Examples of presently preferred alcohols includeoctanol and decanol. An effective amount of alcohol is used in thecurative system. This amount is determined by several factors includingthe desired ratio of alcohol to catalyst, the particular alcohol chosen,and the milling temperature. The particular level for a selectedcomposition is normally a matter of routine experimentation. Generally,this amount is in the range of 0.01 to 10 (more preferably 0.5 to 5)parts by weight alcohol per hundred parts by weight fluoropolymer.

[0103] Thus, a particular composition of the present invention mayinclude two or more fluoropolymer(s) (provided that at least onefluoropolymer includes interpolymerized units derived from anitrogen-containing cure site monomer), a catalyst composition ofFormula (1), a peroxide curative selected to crosslink one or more thanone of the fluoropolymer(s), optionally a coagent such as triallylisocyanurate, and optionally, an alcohol.

[0104] Additives such as carbon black, stabilizers, plasticizers,lubricants, fillers, and processing aids typically utilized influoropolymer compounding can be incorporated into the compositions,provided that they have adequate stability for the intended serviceconditions. In particular, low temperature performance can be enhancedby incorporation of perfluoropolyethers. See, e.g., 1. U.S. Pat No.5,268,405.

[0105] Carbon black fillers are typically also employed influoropolymers as a means to balance modulus, tensile strength,elongation, hardness, abrasion resistance, conductivity, andprocessability of the compositions. Suitable examples include MT blacks(medium thermal black) designated N-991, N-990, N-908, and N-907; FEFN-550; and large particle size furnace iv blacks. When large sizeparticle black is used, 1 to 70 parts filler per hundred partsfluoropolymer (phr) is generally sufficient.

[0106] Fluoropolymer fillers may also be present in the compositions.Generally, from 1 to 50 phr of fluoropolymer filler is used. Thefluoropolymer filler can be finely divided and easily dispersed as asolid at the highest temperature used in fabrication and curing of theinventive composition. By solid, it is meant that the filler material,if partially crystalline, will have a crystalline melting temperatureabove the processing temperature(s) of the curable composition(s). Thepreferred way to incorporate fluoropolymer filler is by blendinglatices.

[0107] This procedure, including various kinds of fluoropolymer filler,is described in U.S. Ser. No. 09/495,600, filed Feb. 1, 2000, thedisclosure of which is herein incorporated by reference.

[0108] One or more acid acceptors can also be added to the formulations.However, where the presence of extractable metallic compounds isundesirable (such as for semiconductor applications) the use ofinorganic acid acceptors should be minimized, and preferably avoidedaltogether. Commonly used acid acceptors include, for example, zincoxide, calcium hydroxide, calcium carbonate, magnesium oxide, silicondioxide (silica), etc. These compounds generally are used in thefluoropolymer formulation to bind any HF or other acids that might begenerated at the high temperatures such as may be encountered duringcuring steps or at the temperatures where the fluoropolymers areintended to function.

[0109] The curable fluoropolymer compositions of the invention may alsobe combined with other curable fluoropolymer compositions such asperoxide-curable fluoropolymer compositions. These additional curablefluoropolymer compositions may also employ small amounts of cure sitemonomers as a comonomer. Suitable cure site monomers are those which,when combined with a curative (e.g., a peroxide) and, preferably acoagent, will provide a cured composition. Preferably these cure sitemonomers include at least one halo group (e.g., a bromo or an iodogroup).

[0110] The curable fluoropolymer compositions can be prepared by mixingone or more fluoropolymer(s), the catalyst, any selected additive oradditives, any additional curatives (if desired), and any otheradjuvants (if desired) in conventional rubber processing equipment. Thedesired amounts of compounding ingredients and other conventionaladjuvants or ingredients can be added to the unvulcanized fluorocarbongum stock and intimately admixed or compounded therewith by employingany of the usual rubber mixing devices such as internal mixers, (e.g.,Banbury mixers), roll mills, or any other convenient mixing device. Thetemperature of the mixture during the mixing process typically shouldnot rise above about 120° C. During mixing, it is preferable todistribute the components and adjuvants uniformly throughout the gum foreffective cure.

[0111] The mixture is then processed and shaped, such as by extrusion(e.g., into the shape of a tube or a hose lining) or by molding (e.g.,in the form of an O-ring seal). The shaped article can then be heated tocure the gum composition and form a cured article.

[0112] Molding or press curing of the compounded mixture usually isconducted at a temperature sufficient to cure the mixture in a desiredtime duration under a suitable pressure.

[0113] Generally, this is between about 95° C. and about 230° C.,preferably between about 150° C. and about 205° C., for a period of fromabout 1 minute to 15 hours, typically from 5 minutes to 30 minutes. Apressure of between about 700 kPa and about 21,000 kPa is usuallyimposed on the compounded mixture in a mold. The molds first may becoated with a release agent and prebaked.

[0114] The cure rheology of the compositions of the present inventionmaintain near their minimum viscosities during typical processingoperations, providing improved scorch resistance and greater options inprocessing conditions over known materials. Significantly, theadvantages in processing do not detrimentally affect the resultingphysical properties of the final cured product and the resultantfluoropolymers of the present invention have excellent high-temperatureproperties and low compression set values.

[0115] The molded mixture or press-cured article is then usuallypost-cured (e.g. in an oven) at a temperature and for a time sufficientto complete the curing, usually between about 150° C. and about 300° C.,typically at about 232° C., for a period of from about 2 hours to 50hours or more, generally increasing with the cross-sectional thicknessof the article. For thick sections, the temperature during the post cureis usually raised gradually from the lower limit of the range to thedesired maximum temperature. The maximum temperature used is preferablyabout 300° C., and this value is held for about 4 hours or more. Thispost-cure step generally completes the cross-linking and may alsorelease residual volatiles from the cured compositions. One example of asuitable post-cure cycle involves exposing molded parts to heat undernitrogen using six stages of conditions. First, the temperature isincreased from 25 to 200° C. over six hours, then the parts are held at200° C. for 16 hours, after which the temperature is increased from 200to 250° C. over 2 hours. Then the parts are held at 250° C. for 8 hours,after which the temperature is 1increased from 250 to 300° C. over 2hours. Then the parts are held at 300° C. for 16 hours. Finally, theparts are returned to ambient temperature such as by shutting off theoven heat.

[0116] The fluoropolymer compositions are useful in production ofarticles such as O-rings, gaskets, tubing, and seals. Such articles areproduced by molding a compounded formulation of the fluoropolymercomposition with various additives under pressure, curing the article,and then subjecting it to a post-cure cycle. The curable compositionsformulated without inorganic acid acceptors are particularly well suitedfor applications such as seals and gaskets for manufacturingsemiconductor devices, and in seals for high temperature automotiveuses.

[0117] The invention will now be described further by way of thefollowing examples.

EXAMPLES

[0118] The indicated results were obtained using the following testmethods, unless otherwise noted. The test results appear in the tablesbelow.

[0119] Cure Rheology:

[0120] Tests were run on uncured, compounded samples using a MonsantoMoving Die Rheometer (MDR) Model 2000 in accordance with ASTM D 5289-93aat 1 77° C., no pre-heat, 30 minute elapsed time, and a 0.5 degree arc.Both the minimum torque (ML) and highest torque attained during aspecified period of time when no plateau or maximum torque was obtained(MH) were measured. Also measured were the time for the torque toincrease 2 units above ML (“t_(s)2”), the time for the torque to reach avalue equal to M_(L)+0.5(M_(H)−M_(L)) (“t′50”), and the time for thetorque to reach M_(L)+0.9(M_(H)−M_(L)) (“t′90”).

[0121] Mooney Scorch:

[0122] Measurements were taken at 121° C., following the proceduresdescribed in ASTM D 1646. Minimum viscosity (units), and the time inminutes to increase to various viscosity levels were recorded. Forexample, the time to reach a 3, 12, and 18 unit rise typically wasrecorded.

[0123] Press-Cure:

[0124] Sample sheets measuring 150×150×2.0 mm were prepared for physicalproperty determination by pressing at about 6.9 Mega Pascal (MPa) for 30minutes at 177° C., unless otherwise noted.

[0125] Post-Cure:

[0126] Press-cured sample sheets were exposed to heat under nitrogenusing the following six stages of conditions: 25 to 200° C. over 6hours; 200° C. for 16 hours; 200 to 250° C. over 2 hours; 250° C. for 8hours; 250 to 300° C. over 2 hours; and 300° C. for 16 hours. Thesamples were returned to ambient temperature before testing.

[0127] Heat Aging:

[0128] Press-cured and post-cured sample sheets were exposed to heat inair for 70 hours at 290° C. and then returned to ambient temperaturebefore testing.

[0129] Physical Properties:

[0130] Tensile Strength at Break, Elongation at Break, and Modulus at100% Elongation were determined using ASTM D 412-92 on samples cut fromthe press-cure or post-cure sheet with ASTM Die D. Units are reportedMPa.

[0131] Hardness:

[0132] Samples were measured using ASTM D 2240-85 Method A with a TypeA-2 Shore Durometer. Units are reported in points on the Shore A scale.

[0133] Compression Set:

[0134] O-ring samples were measured using ASTM 395-89 Method B. TheO-rings had a cross-sectional thickness of 0.139 in. (3.5 mm.). Resultsare reported as a percentage of the original deflection.

[0135] All materials were commercially available from Aldrich ChemicalCo., Milwaukee, Wis. unless otherwise indicated.

[0136] Catalyst Preparation:

[0137] A mixture of 98.66 g of a 40 weight percent (wt %) solution inwater of tetrabutyl phosphonium hydroxide (0.143 mol) (Aldrich) wasneutralized in a 500 mL flask with 8.6 g of acetic acid (99.7% purity).The mixture was swirled for about 5 minutes (pH paper indicated a pH of9). Water was removed from the mixture using a rotary evaporator(rotavap) using a bath temp of around 50° C. until no more watercondensed. Ethanol (100 mL) was added to the flask and the solution wasstripped on the rotavap until no more condensation occurred. Another 100mL of ethanol was added to the solution, following by stripping on therotovap until no more condensation occurred. This yielded 59.95 g of aclear, slightly viscous oil. NMR analysis revealed that this oilcontained 19% ethanol. Karl-Fisher titration revealed that this oilcontained 1.8 wt % water, along with the desired tetrabutyl phosphoniumacetate.

[0138] A mixture of 62.45 g of a 40 wt % solution in water of tetrabutylphosphonium hydroxide (0.0904 mol) (Aldrich) was placed into a 500 mLround bottom flask. Benzoic acid (11.0 g; 0.0904 mol) was added as asolid and dissolved via swirling the flask. Any chunks of benzoic acidwere broken up with a spatula and all the benzoic acid dissolved. Thewater was stripped using a water aspirator vacuum rotavap with a bathtemperature of 50-70° C. When no more water was condensing, the flaskwas removed from the rotavap, and 20 g ethanol was added to the residue.The residue was dissolved and the ethanol was stripped on the samerotavap at the same temperature until no more ethanol condensed. Theethanol addition and stripping was repeated once. This yielded 40.7 g ofa very pale yellow viscous oil that was analyzed to contain a ratio ofvery close to a 1:1:1 adduct of an ethanol:tetrabutylphosphonim:benzoiccomplex.

Example 1

[0139] A fluoroelastomer was prepared by emulsion polymerization whichcontained 65.3 mole percent tetrafluoroethylene (mol % TFE), 33.5 mol %perfluoromethyl vinyl ether (PMVE), and 1.2 mol % of a nitrilegroup-containing cure site monomer, CF₂═CFO(CF₂)₅CN. A catalyst wasprepared by reacting equi-molar amounts of a fluorochemical acid,perfluoro octanoic acid, with sodium methoxide in methanol, then addingan equi-molar amount of tributyl-(2-methoxy)-propyl phosphonium chloridein methanol, and decanting the resulting NaCl to reachtributyl-(2-methoxy)-propyl phosphonium perfluoro octanoate, while theremaining methanol was not stripped.

[0140] The fluoropolymer (100 g basis) was compounded with: 1.5 mmhr ofthe catalyst (dissolved in methanol), and 0.39 g n-octanol.

[0141] Cure rheology tests were run on the uncured, compounded sample.The results are included in Table 2, below. A sheet of the compoundedadmixture was pressed cured and tested and subsequently post-cured. Thepost-cured samples were tested, then heat aged and tested, and finallytested for compression set. All test results are included in the tablesbelow.

Example 2

[0142] The fluoropolymer compound preparation and testing procedures ofExample 1 were followed with the addition of 1 g of triphenyl benzylphosphoniumchloride (TPBCl) to the fluoropolymer mixture duringcompounding.

Example 3

[0143] The fluoropolymer compound preparation and testing procedures ofExample 1 were followed with the addition of 40 g of BaSO₄ and 5 g ofTiO₂ to the fluoropolymer mixture during compounding.

Example 4

[0144] The fluoropolymer compound preparation and testing procedures ofExample 1 were followed with the addition of 1 g of TPBCl (as in Example2) and 15 g MT N990 carbon black to the fluoropolymer mixture duringcompounding.

Example 5

[0145] The fluoropolymer compound preparation and testing procedures ofExample 1 were followed while the catalyst level was increased to 3mmhr, the octanol level was increased to 0.78 g, and 15 g FEF N550carbon black was added the fluoropolymer mixture during compounding.

Example 6

[0146] The fluoropolymer compound preparation and testing procedures ofExample 5 were followed with the addition of 1 g of TPBCl (as in Example2) to the fluoropolymer mixture during compounding.

[0147] These results show the high efficiency of the inventive catalystsystem and the excellent physical properties of the inventivefluoropolymer compositions.

Examples 7-8

[0148] A fluoroelastomer was prepared by emulsion polymerization whichcontained 66.6 mole % TFE, 32.6 mol % PMVE, and 0.8 mol % of a nitrilegroup-containing cure site monomer, CF₂═CFO(CF₂)₅CN. A catalyst wasprepared by reacting equi-molar amounts of a fluorochemical acid,perfluoro butanoic acid, with sodium methoxide in methanol, then addingan equi-molar amount of tributyl-(2-methoxy)-propyl phosphonium chloridein methanol, and decanting the resulting NaCl to reachtributyl-(2-methoxy)-propyl phosphonium perfluoro butyrate, while theremaining methanol was not stripped.

[0149] The fluoropolymer (100 g basis) was compounded with: 2.0 mmhr ofthe catalyst (dissolved in methanol), and 0.39 g n-octanol.

[0150] Example 7 further included 25 g of FEF N550 carbon black. Example8 further included 40 g BaSO₄ and 5 g TiO₂, but no carbon black.

[0151] Cure rheology tests were run on the uncured, compounded samples.A sheet of each compounded admixture was pressed cured and tested andsubsequently post-cured. The post-cured samples were tested, then heataged and tested, and finally tested for compression set.

Examples 9-10

[0152] A fluoroelastomer was prepared as in Examples 7 and 8. A catalystwas prepared by reacting equi-molar amounts of a fluorochemical acid,perfluoro butanoic acid, with sodium methoxide in methanol, then addingan equi-molar amount of triphenylbenzyl phosphonium chloride inmethanol, and decanting the resulting NaCl to reach triphenylbenzylphosphonium IS perfluoro butyrate, while the remaining methanol was notstripped.

[0153] The fluoropolymer (100 g basis) was compounded with: 2.0 mmhr ofthe catalyst (dissolved in methanol), and 0.39 g n-octanol.

[0154] Example 9 further included 25 g of FEF N550 carbon black. Example10 further included 40 g BaSO₄ and 5 g TiO₂, but no carbon black.

[0155] Cure rheology tests were run on the uncured, compounded samples.A sheet of each compounded admixture was pressed cured and tested andsubsequently post-cured. The post-cured samples were tested, then heataged and tested, and finally tested for compression set.

Example 11

[0156] A fluoroelastomer was prepared by emulsion polymerization whichcontained 66.6 mole % TFE, 32.6 mol % PMVE, and 0.8 mol % of a nitrilegroup-containing cure site monomer, CF₂═CFO(CF₂)₅CN. A catalyst wasprepared by reacting equi-molar amounts of a fluorochemical acid,perfluoro propanoic acid, with sodium methoxide in methanol, then addingan equi-molar amount of tributyl-(2-methoxy)-propyl phosphonium chloridein methanol, and decanting the resulting NaCl to reachtributyl-(2-methoxy)-propyl phosphonium perfluoro propanoate, while theremaining methanol was not stripped.

[0157] The fluoropolymer was compounded with a fluoropolymer filler, PFA6502N, commercially available from Dyneon, LLC, St. Paul, Minn. using I00 g fluoropolymer to 25 g filler (125 g total fluoropolymer and filler)in addition to 1.03 mmol of the catalyst (dissolved in methanol), and0.38 g n-octanol.

[0158] Cure rheology and Mooney scorch tests were run on the uncured,compounded, filled fluoropolymer sample. A sheet of the compoundedadmixture was pressed cured and tested and subsequently post-cured. Thepost-cured samples were tested, then heat aged and tested, and finallytested for compression set.

Example 12

[0159] A fluoroelastomer was prepared as in Example 1. Acatalyst-complex solution was prepared by mixing 0.43 g perfluorobutanoic acid, 0.43 g sodium methoxide in methanol (at 25 weight percentsolids), 0.56 g tetrabutyl ammonium chloride in methanol, and 0.40 gn-octanol.

[0160] The fluoropolymer (100 g) was compounded with thecatalyst-complex solution and 25 g MT N990 carbon black.

[0161] Cure rheology tests were run on the uncured, compounded sample. Asheet of the compounded admixture was pressed cured and tested andsubsequently post-cured. The post-cured samples were tested, then heataged and tested, and finally tested for compression set.

Comparative Example 1 (CE-1)

[0162] The fluoropolymer preparation and testing procedures of Example 1were followed except that 1 g hexamethylene tetramine and 15 g FEF N550carbon black was included with 100 g of the fluoropolymer mixture duringcompounding and no inventive catalyst and no alcohol was used.

[0163] The physical properties were comparable to the physicalproperties of the fluoropolymer of Example 5, however the inventivematerial provided improved scorch resistance.

Comparative Example 2 (CE-2)

[0164] A fluoroelastomer was prepared which contained 62.1 mole percenttetrafluoroethylene, 36.8 mole percent perfluoromethyl vinyl ether, and1.1 mole percent of a nitrile group-containing cure site monomer,CF₂═CFO(CF₂)₅CN, by aqueous emulsion polymerization. The resultingpolymer (100 g) was compounded with: 15 g of FEF N550 carbon black and2.0 g of tetraphenyl tin. Cure rheology tests were run on the uncured,compounded sample.

Example 13

[0165] A fluoroelastomer and a catalyst were prepared as in Example 1.

[0166] The fluoropolymer (100 g basis) was compounded with 2.06 g of thecatalyst (dissolved in methanol), and 15 g FEF N550 carbon black, but non-octanol was added.

[0167] Cure rheology and Mooney scorch tests were run on the uncured,compounded sample. The results (included in the tables) show that theExample 13 material had a higher minimum viscosity and a higher maximumviscosity than the Comparative Examples made without the catalyst andfluoropolymer of the invention.

Comparative Examples CE-3, 4, and 5

[0168] A fluoroelastomer was prepared as in Example 1. The fluoropolymer(100 g basis) was compounded with 1.24 g perfluoro octanoic acid and 15g FEF N550 carbon black. CE-4 further included 0.40 g n-octanol. CE-5further included 0.80 g n-octanol.

[0169] Cure rheology and Mooney scorch tests were run on the uncured,compounded samples. The results are included in the tables below.

[0170] The testing was stopped after one hour during Examples 3, 5, and11 and after two hours during Example 13. These results show that theinventive catalyst system provides excellent scorch resistance, muchbetter than in the comparative material.

Example 14

[0171] A first fluoropolymer gum was prepared by emulsion polymerizationwhich contained 62.2 mole percent tetrafluoroethylene (mol % TFE), 36.6mol % perfluoromethyl vinyl ether (PMVE), and 1.2 mol % of a nitrilegroup-containing cure site monomer, CF₂═CFO(CF₂)₅CN.

[0172] A second fluoropolymer gum was prepared by emulsionpolymerization which contained 62.0 mol % TFE, 37.4 mol % PMVE, and 0.6mol % bromotrifluoroethylene.

[0173] A catalyst was prepared by reacting equi-molar amounts of afluorochemical acid, perfluoro octanoic acid, with sodium methoxide inmethanol, then adding an equi-molar amount oftributyl-(2-methoxy)-propyl phosphonium chloride in methanol, anddecanting the resulting NaCl to reach tributyl-(2-methoxy)-propylphosphonium perfluoro octanoate, while the remaining methanol wasstripped.

[0174] A fluoropolymer blend (70 g first fluoropolymer and 30 g secondfluoropolymer basis) was compounded with: 15 grams per hundred grams gum(phr) of FEF N550 carbon black, 1.25 mmhr of the catalyst, 0.8 mmhrperoxide (2,5-dimethyl-2,5-di(t-butyperoxy) hexane, available as Varox®DBPH from R.T. Vanderbilt Co., Norwalk, Conn.), 1.5 gtriallylisocyanurate (TAIC), and 0.4 g n-octanol.

[0175] Cure rheology tests were run on the uncured, compounded sample. Asheet of the compounded admixture was pressed cured and tested andsubsequently post-cured. The post-cured samples were tested, then heataged and tested, and finally tested for compression set.

Examples 15 and 16

[0176] In Example 15, a fluoroelastomer gum was prepared by emulsionpolymerization which contained 62.2 mole percent tetrafluoroethylene(mol % TFE), 36.6 mol % perfluoromethyl vinyl ether (PMVE), and 1.2 mol% of a nitrile group-containing cure site monomer, CF₂═CFO(CF₂)₅CN. Acatalyst was prepared by reacting 0.55 g benzoic acid, 0.64 g NaOCH₃solution in methanol (25% solids), and 1.0 g tributyl-(2-methoxy)-propylphosphonium chloride in methanol (85% solids), and 12 g methanol. Theresulting NaCl was decanted from the catalyst and the remaining methanolwas stripped. Then 3 millimoles catalyst per hundred grams gum (mmhr) ofthe resulting tributyl-(2-methoxy)-propyl phosphonium benzoate catalyst1C was compounded with 100 g of the fluoropolymer gum, 0.8 g n-decanol,and 15 grams per hundred grams gum (phr) of FEF N550 carbon black.

[0177] In Example 16, a fluoropolymer gum was prepared and compounded asabove except that the same quantity (3 mmhr) of atributyl-(2-methoxy)-propyl phosphonium acetate catalyst wassubstituted. This catalyst was prepared by the method described aboveexcept that an equi-molar amount of glacial acetic acid was substitutedfor the benzoic acid.

[0178] Cure rheology tests were run on the uncured, compounded samples.Sheets of the compounded admixtures were pressed cured and tested andsubsequently post-cured. The post-cured samples were tested, then heataged and tested, and finally tested for compression set.

Example 17

[0179] A fluoropolymer was prepared by emulsion polymerization whichcontained 62.0 mol % TFE, 37.4 mol % PMVE, and 0.6 mol %bromotrifluoroethylene. This fluoropolymer (30 g) was compounded with:70 g of the fluoroelastomer of Example 15, 1.5 mmhr of the catalyst ofExample 1, 0.6 mmhr peroxide (2,5-dimethyl-2,5-di(t-butyperoxy) hexane,available as Varox® DBPH from R.T. Vanderbilt Co., Norwalk, Conn.), 1 gtriallylisocyanurate (TAIC), 15 phr FEF N550 carbon black, and 0.4 gn-octanol.

[0180] Cure rheology tests were run on the uncured, compounded sample. Asheet of the compounded admixture was pressed cured and tested andsubsequently post-cured. The post-cured samples were tested, then heataged (70 h at 270° C.) and tested, and finally tested for compressionset. All test results are included in the tables below.

[0181] In the following tables, N/M indicates that the property was notmeasured, TS was used for Tensile Strength, Elong. was used forelongation, and Mod. was used for modulus. TABLE 1 CE 1 and CE 2 ResultsCE-1 CE-2 M_(L) (N m) 0.156 0.228 M_(H) (N m) 1.386 1.773 t_(s)2 (min)1.78 0.48 t'50 (min) 3.72 0.76 t'90 (min) 39.28 5.75 After Press Cureand Post Cure: Tensile Strength at Break (MPa) 13.1 13.75 Elongation atBreak (%) 95 144 100% Modulus (MPa) — 7.39 Shore A Hardness 73 72Compression Set (%) 70 hrs at 200° C. 15.5 59.5 Compression Set (%) 70hrs at 230° C. — 76.6 Compression Set (%) 22 hrs at 300° C. — 100 AfterHeat Aging: Tensile Strength at Break (MPa) 11.86 Elongation at Break(%) 250 100% Modulus (MPa) 3.65 Shore A Hardness 71

[0182] TABLE 2 Test Results Example 1 2 3 4 5 6 7 8 9 10 11 12 14 CureRheology: M_(L) (Nm) 0.053 0.037 0.063 0.07 0.064 0.088 0.096 0.0850.146 0.188 0.182 0.113 1.198 M_(H) (Nm) 0.473 0.489 1.2 0.603 1.0530.888 0.635 1.078 0.347 0.44 0.833 1.245 0.112 t_(s) 2 (min) 12.46 7.795.35 5.39 3.78 1.87 5.93 3.26 n/a 9.63 10.88 8.54 2.28 t'50 12.19 7.796.93 6.41 4.63 2.21 6.16 4.11 3.05 3.71 11.7 9.33 8.14 (min) t'90 20.7621.34 14.32 18.91 13.45 5.68 9.02 7.49 11.87 9.81 19.63 12.15 7.67 (min)After Press-Cure and Post-Cure: TS at 6.56 6.7 11.6 12.14 14.09 16.7814.78 12.58 12.12 11.73 13.51 19.57 9.57 Break (MPa) Elong. at 230 218155 163 108 107 219 232 237 326 229 156 300 Break (%) 100% 1.39 1.426.56 3.77 12 14.93 6.18 5.69 5.17 3.94 4.21 8.25 2.83 Mod. (MPa) Shore A55 55 70 68 77 77 78 71 73 70 72 73 71 Hardness After Heat-Aging: TS at9.38 6.83 9.38 13.58 15.87 14.67 10.34 8.92 8.54 6.91 12.76 13.11 8.23Break (MPa) Elong. at 272 234 210 206 155 120 302 305 345 397 250 181357 Break (%) 100% 1.25 1.29 4.61 2.92 7.6 11.17 3.94 3.41 3.03 2.523.94 5.8 2.22 Mod. (MPa) Shore A 55 55 71 66 74 77 73 70 72 67 70 72 70Hardness Weight 1.4 0.95 1.85 0.8 1.1 1 1 0.9 1.1 1.2 N/M 1.4 0.9 Loss(%)

[0183] TABLE 3 Test Results Example: 15 16 17 Cure Rheology M_(L) (N m)0.0926 0.0994 0.1333 M_(H) (N m) 0.8361 0.8406 0.9943 t_(s)2 (min) 4.552.36 0.9 t'50 (min) 6.72 3.17 1.39 t'90 (min) 22.11 8.53 5.36 PressCured and TS at Break (MPa) 16.42 15.73 13.96 Post Cured Elongation atBreak (%) 114 110 145 100% Modulus (MPa) 12.69 13.11 7.81 Shore AHardness 75 74 74 Heat Aged* TS at Break (MPa) 14.09 14.95 9.86Elongation at Break (%) 150 153 211 100% Modulus (MPa) 7.14 8.12 3.50Shore A Hardness 73 71 71 Weight Loss (%) 1.4 1.1 1.4

[0184] Example 17 was heat aged for 70 h at 270° C. rather than the 290°C. of the other examples. TABLE 4 Cure Rheology Example Number: 13 CE-3CE-4 CE-5 M_(L) (N m) 0.099 0.070 0.067 0.050 M_(H) (N m) 1.557 0.1070.095 0.249 t_(s)2 (min) 4.79 — — — t'50 (min) 5.79 33.12 7.89 50.34t'90 (min) 9.41 55.47 39.06 57.91

[0185] The designation “--” indicates that no viscosity increase wasobserved. TABLE 5 Compression Set Example: 1 2 3 4 5 6 7 8 70 hrs at N/M8.7 10.6 11.9 10.9 11 15 12.2 200° C. 70 hrs at N/M 14.41 13 13.9 15.616.6 19 20.4 230° C. 70 hrs at N/M N/M 33.8 26.7 26.5 28.6 N/M N/M 290°C. Example: 9 10 11 12 14 15 16 17 70 hrs at 26.5 21.3 16.3 14.6 50.111.6 10.9 32.8 200° C. 70 hrs at 29.8 25.9 22.5 20.4 62.5 13.4 15.5 59.8230° C. 70 hrs at N/M N/M 47 39.6 72.5 27.4 28.7 *91.2 290° C.

[0186] The asterisk on the third compression set test for Example 17indicates that 70 h at 270° C. was used, rather than 290° C. TABLE 6Mooney Scorch Exam- ple 3 5 11 13 15 16 CE-1 Min- 53.2 42.2 58.8 49.57.095 5.932 74.1 imum vis- cosity t-3 — — — — >120 >120 5.83 (min) t-10— — — — >120 >120 9.91 (min) t-18 — — — — >120 >120 13.91 (min)

[0187] A number of embodiments of the invention have been described.Nevertheless, it will be understood that various modifications may bemade without departing from the spirit and scope of the invention.

What is claimed is:
 1. A composition comprising: (a) a fluoropolymercomprising interpolymerized units derived from a nitrogen-containingcure site monomer; (b) a catalyst composition that includes a compoundhaving the general formula: {RA}⁽⁻⁾{QR′_(k)}⁽⁺⁾ or the precursorsthereof added separately or as a mixture; wherein R is a C₁-C₂₀ alkyl oralkenyl, C₃-C₂₀ cycloalkyl or cycloalkenyl, or C₆-C₂₀ aryl or aralkyl,which may be nonfluorinated, partially fluorinated, or perfluorinated, Ais an acid anion or an acid derivative anion, Q is phosphorous, sulfur,nitrogen, arsenic, or antimony, each R′ is, independently, hydrogen or asubstituted or unsubstituted C₁-C₂₀ alkyl, aryl, aralkyl, or alkenylgroup, provided that when Q is nitrogen and the only fluoropolymer inthe composition consists essentially of a terpolymer oftetrafluoroethylene, a perfluorovinylether, and a perfluorovinylethercure site monomer comprising a nitrile group not every R′ is H, and k isthe valence of Q; and optionally (c) an alcohol of the general formulaR²—OH, wherein R² is an alkyl group having from 1 to 20 carbon atoms,and wherein R² can be fluorinated.
 2. A composition according to claim 1wherein A is selected from the group consisting of: COO, O when R isaryl or alkylaryl, SO₃, SO₂, SO₂NH, PO₃, CF₃CF(CF₃)CH₂O,C_(n)F_(2n+1)CH₂O wherein n is 0 to 100, CH₂OPO₃, (CH₂O)₂PO₂, C₆H₄O,OSO₃,

and

wherein R′ is as defined in claim
 1. 3. A composition according to claim1 wherein R is selected from a non-fluorinated, partially-fluorinated,or perfluorinated group.
 4. A composition according to claim 1 whereinRA has the general formula selected from RCOOM, ROSO₃M, RSO₃M, and ROM,wherein M is hydrogen, or an alkali or alkaline earth metal.
 5. Acomposition according to claim 1 wherein RA is selected from the formulaR_(x)—Ph_(y)—{(CH₂)_(n)—D}m wherein each R_(x) is the same or differentC₁-C₁₀ alkenyl or alkyl, x is 0 to 5, y is 0 or 1, n is 0 to 10, m is 1to 5, and D is selected from COO, OSO₃, SO₃, and O (when y is 1),provided that the sum of x and m is 6 or less and provided that x and yare not both zero; RCOO wherein R is alkenyl, an alkyl of 1 to 10 carbonatoms, or an aryl of 6 to 20 carbon atoms; ⁽⁻⁾OOC—(CX₂)_(n)—COO⁽⁻⁾wherein n is 0 to 10, X=H, F, or Cl; and Ph—((CH₂)_(p)—COO⁽⁻⁾)_(q)wherein p and q are independently 1 to 4; CF₃ CF(CF₃)CH₂O orC_(n)F_(2n+1)CH₂O wherein n is 0 to 100; and blends of two or more suchcompounds.
 6. A composition according to claim 1 wherein RA is selectedfrom the general formula (−)O_(z)—Ph—G_(y)—Ph—O_(z) ⁽⁻⁾ wherein G is abond or a difunctional aliphatic, cycloaliphatic, or C₁-C₁₃ aromaticradical, or a thio, oxy, carbonyl, sulfinyl, or sulfonyl radical, Gand/or Ph are optionally substituted with at least one Cl or F atom, yis 0 or 1, each z is, independently, 1 or 2, and any aromatic ring ofthe polyoxy compound is optionally substituted with at least one atom ofCl, F, or Br atom, or carboxyl, or an acyl radical, or an alkyl radical;and blends of two or more such compounds.
 7. A composition according toclaim 1 wherein RA is selected from the general formula⁽⁻⁾O—Ph—C(CX₃)₂—Ph—O⁽⁻⁾, wherein X is H, Cl, or F; and blends of two ormore such compounds.
 8. A composition according to claim 1 whereinQR′_(k) is selected from tetramethylphosphoniums,tributylallylphosphoniums, tributylbenzylphosphoniums,dibutyldiphenylphosphoniums, tetrabutylphosphonium, tributyl(2-methoxy)propylphosphoniums, triphenylbenzylphosphoniums, andtetraphenylphosphoniums.
 9. A composition according to claim 1 whereinQR′_(k) is selected from phenyltrimethylammoniums, tetrapentylammoniums,tetrapropylammoniums, tetrahexylammoniums, tetraheptylammoniums,tetramethylammoniums, tetrabutylammoniums, tributylbenzyl ammoniums,tributylallylammoniums, tetrabenzylammoniums, tetraphenylammoniums,diphenyl diethylamino ammoniums, triphenylbenzylammoniums,8-benzyl-1,8-diazabicyclo[5.4.0]undec-7-eniums,benzyltris(dimethylamino) phosphoniums, and bis(benzyldiphenylphosphine)iminiums.
 10. A composition of claim 1 wherein the catalystcomposition is prepared in situ.
 11. A composition according to claim 1wherein the catalyst composition is prepared from components dissolvedin a solvent.
 12. A composition according to claim 1 wherein thefluoropolymer comprises interpolymerized units derived from (i)tetrafluoroethylene, and optionally (ii) one or more perfluorovinylethers of the formula: CF₂═CFO(R² _(f)O)_(a)(R³ _(f)O)_(b)R⁴ _(f)wherein R² _(f) and R³ _(f) are the same or are different linear orbranched perfluoroalkylene groups of 1-6 carbon atoms; a and b are,independently, 0 or an integer from 1 to 10; and R⁴ _(f) is aperfluoroalkyl group of 1-6 carbon atoms.
 13. A composition according toclaim 12 wherein the fluoropolymer further comprises interpolymerizedunits derived from monomers selected from the group consisting ofperfluoroolefins, partially-fluorinated olefins, non-fluorinatedolefins, vinylidene fluoride, and combinations thereof.
 14. Acomposition according to claim 1 wherein said cure site monomer isselected from a fluorinated olefin and a nitrile-containing monomer. 15.A composition according to claim 1 wherein said cure site monomer is anitrile-containing monomer having the formula CF₂═CFO(CF₂)_(L)CN;CF₂═CFO(CF₂)_(u)OCF(CF₃)CN; CF₂═CFO[CF₂CF(CF₃)O]_(q)(CF₂O)_(y)CF(CF₃)CN;or CF₂═CF[OCF₂CF(CF₃)]_(r)O(CF₂)_(t)CN; wherein L=2-12; q=0-4; r=1-2;y=0-6; t=1-4, and u=2-6; andperfluoro(8-cyano-5-methyl-3,6-dioxa-1-octene).
 16. A compositionaccording to claim 1 further comprising a filler selected fromfluoropolymer filler, carbon black, and combinations thereof.
 17. Thecomposition of claim 1 wherein the fluoropolymer is selected from afluoroelastomer and a fluoroplastic.
 18. The composition of claim 1wherein the composition has an induction time below about 15 minutes ata temperature of about 175° C.
 19. The composition of claim 1 whereinthe composition has a scorch resistance greater than the scorchresistance of a comparative composition tested at the same temperature,which comparative composition has the same fluoropolymer composition ofclaim 1 but with a urotropin curative.
 20. The composition of claim 1further comprising an additional curative material.
 21. The compositionof claim 20 wherein the additional curative material is selected fromammonia-generating compounds, substituted triazine derivatives,unsubstituted triazine derivatives, peroxides, bis-aminophenols,bis-amidooximes, and organotin compounds.
 22. A shaped articlecomprising the fluoropolymer composition of claim
 1. 23. The compositionof claim 1 further comprising a fluoropolymer containinginterpolymerized units derived from monomers selected from the groupconsisting of perfluoroolefins, partially-fluorinated olefins,non-fluorinated olefins, vinylidene fluoride, perfluorovinyl ethers, andcombinations thereof.
 24. The composition according to claim 23comprising a curative that increases MDR torque in the fluoropolymercomposition at 177° C. by at least about 0.01 N m.
 25. The compositionof claim 23 further comprising a curative material selected fromammonium salts, ammonia-generating compounds, substituted triazinederivatives, unsubstituted triazine derivatives, peroxides,bis-aminophenols, bis-amidooximes, and organotin compounds; andoptionally a coagent.
 26. The composition of claim 25 wherein thecoagent is selected from triallyl cyanurate; triallyl isocyanurate;tri(methylallyl) isocyanurate; tris(diallylamine)-s-triazine; triallylphosphite; N,N-diallyl acrylamide; hexaallyl phosphoramide,N,N,N′,N′-tetraalkyl tetraphthalamide; N,N,N′,N′-tetraallyl malonamide;trivinyl isocyanurate; 2,4,6-trivinyl methyltrisiloxane; andtri(5-norbornene-2-methylene)cyanurate.
 27. The composition of claim 25wherein the additional fluoropolymer includes interpolymerized unitscontaining a halogen that is capable of participation in a peroxide curereaction and wherein the additional curative is a peroxide, andoptionally further comprising a triallyl cyanurate coagent.
 28. A shapedarticle comprising the fluoropolymer composition of claim
 23. 29. Thecomposition of claim 1 wherein RA is selected from the formulaCF₃(CF₂)_(n)COO⁽⁻⁾ wherein n is 1, 2, or 6, and wherein QR′_(k) isselected from tetrabutylphosphonium andtributyl(2-methoxy)propylphosphonium.
 30. The composition of claim 1wherein RA is selected from the formula (−)OOC(CF₂)_(n)COO⁽⁻⁾ wherein nis 2 or 4, and wherein QR′_(k) is selected from tetrabutylphosphoniumand tributyl(2-methoxy)propylphosphonium.
 31. The composition of claim 1wherein RA is selected from acetate and benzoate, and wherein QR′_(k) isselected from tetrabutylphosphonium andtributyl(2-methoxy)propylphosphonium.
 32. A method of making afluoropolymer composition comprising the steps of: a) forming a mixturecomprising a fluoropolymer having interpolymerized units derived from anitrogen-containing cure site monomer, a catalyst composition comprisinga compound having the formula: {RA}⁽⁻⁾{QR′_(k)}⁽⁺⁾ or the precursorsthereof added separately or as a mixture, wherein R is a C₁-C₂₀ alkyl oralkenyl, C₃-C₂₀ cycloalkyl or cycloalkenyl, or C₆-C₂₀ aryl or alkylaryl,A is an acid anion or an acid derivative anion group, which may beheterocyclic, Q is P, S, N, As, or Sb, and each R′ is, independently,hydrogen or a substituted or unsubstituted C₁-C₂₀ alkyl, aryl, aralkyl,or alkenyl group, provided that when Q is nitrogen and the onlyfluoropolymer in the composition consists essentially of a terpolymer ofTFE, a perfluorovinylether, and a perfluorovinylether cure site monomercomprising a nitrile group not every R′ is H, and k is the valence of Q,and optionally in the presence of an alcohol of the general formulaR²—OH, wherein R₂ is a C₆-C₂₀ alkyl group; b) shaping the mixture; c)curing the shaped mixture; and optionally d) heat aging the curedmixture.
 33. A method according to claim 32 wherein the catalyst isadded in a form selected from a compound and a mixture of catalystprecursors.
 34. A method according to claim 32 wherein individualcomponents of the catalyst are separately added to the fluoropolymercomposition.
 35. A method according to claim 32 wherein the step ofcuring further comprises press-curing and optionally post-curing.
 36. Acured article prepared according to the method of claim
 32. 37. A methodfor increasing the induction period in a curable fluoropolymercomposition comprising the steps of: a) providing a fluoropolymercomprising interpolymerized units derived from a nitrogen-containingcure site monomer; and b) incorporating, into the fluoropolymer, acatalyst composition that includes a compound having the generalformula: {RA}⁽⁻⁾{QR′_(k)}⁽⁺⁾ or the precursors thereof added separatelyor as a mixture, wherein R is a C₁-C₂₀ alkyl or alkenyl, a C₃-C₂₀cycloalkyl or cycloalkenyl or a C₆-C₂₀ aryl or alkylaryl; A is an acidanion or an acid derivative anion; Q is P, S, N, As, or Sb; each R′ is,independently, hydrogen or a substituted or unsubstituted C₁-C₂₀ alkyl,aryl, aralkyl, or alkenyl group, provided that when Q is N and the onlyfluoropolymer in the composition consists essentially of a terpolymer ofTFE, a perfluorovinylether, and a perfluorovinylether cure site monomercomprising a nitrile group not every R′ is H; and k is the valence of Q.38. The method of claim 37 further comprising the step of incorporatingan alcohol of the general formula R²—OH, wherein R² is a C₁-C₂₀ alkylgroup, and wherein R can be fluorinated.
 39. The method of claim 37further comprising the step of: c) shaping the composition.
 40. Themethod of claim 37 further comprising the step of: d) curing the shapedcomposition; and optionally e) heat aging the cured composition.
 41. Themethod of claim 40 wherein the step of curing includes press-curing, andoptionally post-curing.
 42. A shaped article prepared according to themethod of claim 37.